The objective of this study is to determine what role prolactin plays in the growth, maintenance and treatment of human breast and prostate cancer. A multifaceted approach using in vitro and in vivo studies is envisioned. Normal and cancerous breast and prostate tissue obtained during routine surgical procedures including reduction mammoplasty, mastectomy, suprapubic prostatectomy and transurethral resection will be grown in organ culture under the influence of prolactin and other hormones. Informed consent for use of these tissues will be obtained. Clinical studies will involve prolactin stimulation utilizing chlorpromazine in a single dose of 25 mg IM and thyrotropin releasing hormone in an IV dose of 100 micrograms. The ability to suppress prolactin will be tested by giving a single oral dose of 500 mg L-dopa or a single dose of 2-Br-alpha-ergocryptine (CB154). These tests will be carried out in normal volunteers, patients with breast or prostate cancer and before, during and after routine surgical or pharmacologic therapy is instituted for the treatment of these diseases. In a few cases the patients may undergo testing for gonadotropin reserve using a single IV dose of 150 micrograms of gonadotropin releasing hormone (Gn-RH). In some a routine insulin tolerance test may be carried out. All of the above tests will entail blood sampling before and after administration of the drugs. We have recently developed an assay to measure a human milk protein called alpha-lactalbumin. The details are spelled out in this year's Progress Report which is being submitted to the Research and Education Committee with these forms. We will measure the protein in the cultures described above and in some instances blood will be drawn from patients and volunteers to measure alpha-lactalbumin in various clinical states.